1. |
2. Chemical and structural investigation of the cobalt phthalocyanineMatija Stupar, 2015, magistrsko delo Opis: In the last two decades, studies on organic molecules mimicking substances of fundamental importance in nature, like chlorophyll or hemoglobin, have attracted researchers’ attention. These molecules are building blocks for a family of materials also referred to as “organic semiconductors”. Such compounds can be implemented in numerous applications, ranging from data-storage to light harvesting. Some of their fundamental advantages include low cost, light weight, relatively easy engineering and mechanical flexibility, compatible with bending plastic substrates.
In this thesis work we investigated the chemical, structural and electronic properties of cobalt phthalocyanines (CoPc). These molecules have promising applications in the field of magnetic data storage and spintronics in general, due to the ferromagnetic properties of the cobalt atom. Several techniques like photoemission core-level spectroscopy and valence band spectroscopy, together with X-ray absorption, have been used in order to determine the CoPc properties in gaseous phase, i.e. in the absence of interaction with the surrounding environment.
Another set of experiments was devoted to the commissioning of the CITIUS time-resolved photoemission setup, that will be used in future studies of CoPc molecules on surfaces.
Najdeno v: osebi
Ključne besede: Cobalt phthalocyanine (CoPc), photoemission spectroscopy (PES), X-ray absorption spectroscopy (XAS), synchrotron radiation, laser, high order harmonic generation (HHG), time resolved spectroscopy
Objavljeno: 29.09.2015; Ogledov: 7635; Prenosov: 268
 Polno besedilo (2,96 MB) |
3. Advantages and disadvantages of experiments with ultrashort two-color pulsesMatija Stupar, 2020, doktorska disertacija Opis: Advances in the development of lasers have led to a new class of radiation sources generating coherent, tunable, ultrashort light pulses in the spectral region ranging from infrared to soft X-rays. This includes high-order harmonics generation in gas (HHG), on which relies the CITIUS facility at University of Nova Gorica (Slovenia), and free-electron lasers (FELs), such as the facility FERMI at Elettra-Sincrotrone Trieste (Italy). The distinctive structure of HHG and FEL radiation paved the way to time-resolved experiments, which are performed to investigate events occurring on a short, or very short, temporal scale, from picoseconds to femtoseconds.
This work focuses on the advantages and disadvantages of some experimental techniques based on using these novel light sources to investigate the microscopic and/or ultrafast dynamics of matter samples, which have been previously driven out of equilibrium.
Advantages rely on the implementation of various applications based on two-color schemes and, more specifically, include the possibility of acquiring two-dimensional frequency maps, measuring electrons’ effective masses, or investigating electronic properties decoupled from the influence of the lattice. Particular focus will be put on experimental methods relying on photoelectric effect and photoelectron spectroscopy. In all experiments, we took advantage of one or more specific properties of HHG and FEL sources, such as controllable chirp, to study laser dressed states in helium, variable polarization, to study electronic properties of iron-based pnictides and ultrashort pulses (< 10 fs) to study the purely electronic dynamics in transition metal dichalcogenides.
On the other hand, the study of the interface between a molecule and a topological insulator revealed some intrinsic limitations and physical drawbacks of the technique, such as spurious effects originating from the high power pulses, like multiphoton absorption and the space charge effect, or the reduction of experimental resolution when pushing for shorter and shorter pulse durations. Some disadvantages are also connected to the current state-of-the-art in the field of ultrashort laser systems, where a trade-off needs to be found between repetition rate and laser power.
Finally, state-of-the-art experiments based on the ability to generate ultrashort pulses carrying orbital angular momentum in visible, near-infrared as well as extreme UV range will be presented. The use of these pulses opens the door to the investigation of new physical phenomena, such as probing magnetic vortices using extreme ultraviolet light from a free-electron laser or imprinting the spatial distribution of an ultrashort infrared pulse carrying orbital angular momentum onto a photoelectron wave packet.
Najdeno v: osebi
Ključne besede: ultrafast lasers, two-color experiments, photoemission, high-order harmonic generation, free-electron lasers, hot-electrons dynamics, surface science, pump-probe photoemission, ultraviolet photoemission, orbital angular momentum
Objavljeno: 02.12.2020; Ogledov: 2582; Prenosov: 94
Polno besedilo (19,78 MB) |
4. New strategy for magnetic gas sensingRoberta Ciprian, Piero Torelli, Angelo Giglia, B Gobaut, Barbara Ressel, Janez Štupar, Matija Stupar, Antonio Caretta, Giovanni De Ninno, Tommaso Pincelli, Barbara Casarin, Ganesh Adhikari, G Sberviglieri, C Baratto, Marco Malvestuto, 2016, izvirni znanstveni članek Najdeno v: osebi
Ključne besede: hybrid nanostructures, sensor, absorption spectroscopy
Objavljeno: 05.02.2018; Ogledov: 3134; Prenosov: 0
Polno besedilo (2,25 MB) |
5. Conclusively Addressing the CoPc Electronic Structure: A Joint Gas- Phase and Solid-State Photoemission and Absorption Spectroscopy StudyMarcello Coreno, Monica de Simone, Ieva Bidermane, Y. Sassatelli, R. Ovsyannikov, Erika Giangrisostomi, C. Grazioli, J. Lüder, Valeria Lanzillotto, I.E. Brumboiu, Teng Zhang, Barbara Ressel, Matija Stupar, Maddalena Pedio, Petra Rudolf, Barbara Brena, Carla Puglia, 2017, izvirni znanstveni članek Najdeno v: osebi
Ključne besede: Cobalt Phtalocyanine, photoemission spectroscopy, gas phase, solid state
Objavljeno: 07.02.2018; Ogledov: 3399; Prenosov: 0
Polno besedilo (1,38 MB) |
6. Orbital-dependent electron dynamics in Fe-pnictide superconductorsA. Thamizhavel, Damjan Krizmancic, Giovanni De Ninno, Jurij Urbančič, Primož Rebernik Ribič, Barbara Ressel, Ganesh Adhikary, Kalobaran Maiti, Matija Stupar, 2018, izvirni znanstveni članek Opis: We report on orbital-dependent quasiparticle dynamics in EuFe 2 As 2, a parent compound of Fe-based superconductors, and a way to experimentally identify this behavior using time-and angle-resolved photoelectron spectroscopy across the spin density wave transition. We observe two different relaxation timescales for photoexcited d x z/d y z and d x y electrons. While the itinerant d x z/d y z electrons relax faster through the electron-electron scattering channel, d x y electrons form a quasiequilibrium state with the lattice due to their localized character, and the state decays slowly. Our findings suggest that electron correlation in Fe pnictides is an important property, which should carefully be taken into account when describing the electronic properties of both parent and carrier-doped compounds, and therefore establish a strong connection with cuprates
Najdeno v: osebi
Ključne besede: photoelectron dynamics, Fe based superconductors
Objavljeno: 29.11.2018; Ogledov: 2777; Prenosov: 0
Polno besedilo (2,37 MB) |
7. Interface phenomena between CdTe and ZnTe: Cu back contactAlessio Bosio, Roberta Ciprian, Alessio Lamperti, I Rago, Barbara Ressel, Greta Rosa, Matija Stupar, E Weschke, 2018, izvirni znanstveni članek Opis: Thin film technology has reached a maturity to achieve conversion efficiencies of the order of 22%. Among thin films, CdTe-based photovoltaic modules represent 80% of the total production. Nonetheless, some issues concerning back-contact are still open. In industrial process a chemical etching is required in order to make the CdTe film surface rich in Te. The Te-excess is fundamental in order to form a stable telluride compound with copper and to obtain an ohmic, low-resistance back-contact. Moreover, the Te-excess hinders the fast diffusion of copper in CdTe and its achievement of the junction region, preventing the destruction of the device. In this paper we study a ZnTe:Cu buffer layer deposited onto a CdTe film, characterized by a naturally Te-rich surface obtained with a particular chlorine heat treatment without any chemical etching. Copper diffusion and the CdTe/ZnTe:Cu interface were studied by x-ray
Najdeno v: osebi
Ključne besede: solar cells, CdTe, ZnTe:Cu back contact
Objavljeno: 29.11.2018; Ogledov: 2993; Prenosov: 0
Polno besedilo (2,23 MB) |
8. Light-Induced Magnetization at the NanoscaleGiovanni De Ninno, Jamal Berakdar, Carlo Callegari, Marco Zangrando, Matjaž Žitnik, Matija Stupar, Simone Spampinati, Alberto Simoncig, Benedikt Rösner, Barbara Ressel, Oksana Plekan, Najmeh Mirian, Andrej Mihelič, Michael Meyer, Michele Manfredda, Špela Krušič, Klavs Hansen, Luca Giannessi, Christian David, Alexander Demidovich, Michele Di Fraia, Miltcho Danailov, Marcello Coreno, Primož Rebernik Ribič, Jonas Wätzel, 2022, izvirni znanstveni članek Najdeno v: osebi
Ključne besede: FEL, orbital angular momentum, magnetisation
Objavljeno: 16.01.2023; Ogledov: 144; Prenosov: 0
Polno besedilo (1,39 MB) |
9. Tunable orbital angular momentum in high-harmonic generationDavid Gauthier, Primoz Rebernik-Ribic, Ganesh Adhikari, A Camper, C Chappuis, LF Dimauro, G Dovillaire, Fabio Frassetto, R Geneaux, Paolo Miotti, Luca Poletto, Barbara Ressel, C. Spezzani, Matija Stupar, T Ruchon, Giovanni De Ninno, 2017, izvirni znanstveni članek Najdeno v: osebi
Ključne besede: Angular orbital momentum, High harmonic generation
Objavljeno: 05.02.2018; Ogledov: 3358; Prenosov: 750
Polno besedilo (843,67 KB) |
10. Coupling of autoionizing states by a chirped laser pulseBarbara Ressel, Jurij Urbančič, Primož Rebernik Ribič, Špela Krušič, Žiga Barba, Mateja Hrast, Klemen Bučar, Andrej Mihelič, Matjaž Žitnik, Matija Stupar, David Gauthier, Giovanni De Ninno, 2020, objavljeni povzetek znanstvenega prispevka na konferenci Opis: We have observed the autoionization of the laser-coupled 2s2p 1Po and 2p2 1Se resonances in helium. The ions were collected while varying the frequency and delay of the extreme-ultraviolet (EUV) excitation pulse with respect to the linearly chirped visible (VIS) laser pulse. From the measured frequency-delay map the Autler- Townes splitting, the EUV-VIS cross-correlation and the linear chirp parameter were extracted.
Najdeno v: osebi
Ključne besede: High Harmonic Generation
Objavljeno: 29.06.2020; Ogledov: 2236; Prenosov: 0
Polno besedilo (654,72 KB) |
